78985A 1 Mercruiser THERMOSTAT HOUSING ASSEMBLY(INBOARD)

Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Dispose of all fluids according to local regulations and mandates.
Drain the coolant from the cooling system into a suitable container for storage or disposal. Refer to Operation and Maintenance Manual, "Cooling System Coolant - Drain" for more information.
Illustration 1 g06214418
Typical example
Three different types of plate can be installed between the cylinder block and the water pump (3)
Illustration 2 g06214498
Typical example
Loosen the hose clamp and disconnect the coolant hose assembly from inlet connection (4) on water pump (3).
Disconnect the harness assembly from coolant temperature sensor (1).
Remove bolts (2) and nut (5) from water pump (3). Support the water pump as the bolts and nut are removed.
Remove water pump (3) from the cylinder block.Note: If necessary, gently tap the water pump with a soft faced hammer to loosen the water pump.
Remove gasket (6).
Water pump (3) could have plate (7), plate (7a), or plate (7b) installed to the water pump.
Remove gasket (8).
If necessary, remove coolant temperature switch (1) from water pump (3).Installation Procedure
Table 1
Required Tools
Tool Part Number Part Description Qty
A - Loctite 242 1
Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Ensure that the gasket surfaces of the water pump, plate, and the cylinder block are clean and free from damage.
Ensure that all components of the water pump are free from wear or damage. Replace any components that are worn or damaged.
Illustration 3 g06214701
Ensure that the bolt holes in Position (W) and stud (9) are clean and free from oil and coolant.
Install a new gasket (6) over stud (9). Ensure that the gasket is correctly oriented. Refer to Illustration 3.
Illustration 4 g06214418
Typical example
Three different types of plate can be installed between the cylinder block and the water pump (3)
Illustration 5 g06214731
Typical example
Illustration 6 g06214737
Water pump bolts and nut tightening sequence
Install a new gasket (6) over stud (9). Ensure that the gasket is correctly oriented.
Install either plate (7), plate (7a), or plate (7b) over stud (9). Ensure that the plate is correctly oriented.
Install a new gasket (8) over stud (9). Ensure that the gasket is correctly oriented.
Apply Tooling (A) to the first two threads of bolts (2) and nut (5).
Install water pump (3).
Install bolts (2) and nut (5) hand tight. Ensure that the gaskets are correctly positioned.
Tighten bolts (2) and nut (5) to a torque of 5 N m (44 lb in) in the sequence shown in Illustration 6.
Tighten bolts (2) and nut (5) to a torque of 10 N m (89 lb in) in the sequence shown in Illustration 6.
Illustration 7 g06214739
If necessary, apply Tooling (A) to the first two threads of coolant temperature switch (1). Install the coolant temperature switch to water pump (3). Tighten the coolant temperature switch to a torque of 27 N m (239 lb in).
Connect the coolant hose assembly to inlet connection (4) on water pump (3). Securely tighten the hose clamp.
Connect the harness assembly to coolant temperature sensor (1).
Fill the cooling system with coolant. Refer to Operation and Maintenance Manual, "Cooling System Coolant - Fill" for the correct procedure.End By:
Install the fan. Refer to Disassembly and Assembly, "Fan - Remove and Install" for the correct procedure.